Electrical communication in and out of an array of thin wires, especially arrays having wires thinner than 1000 nanometers, can be difficult. One reason for this difficulty is that thin wires in arrays are often spaced closely together. This close spacing can make connecting an electrical bond pad with each wire impractical.
One structure for electrically connecting to wires of an array is called a multiplexing/demultiplexing architecture (a “mux/demux architecture”). The mux/demux architecture does not need an electrical bond pad to be connected or aligned with each wire of an array. Instead, one bond pad is typically connected to all of the wires of the array.
This one bond pad does not, however, allow communication with each wire of the array individually. To differentiate between wires, address elements, such as transistors, can be contacted with each of the wires. For a 16-wire array, for instance, four transistors can be contacted with each wire. By selectively turning the transistors on and off, only one of the 16 wires can be permitted to communicate with the one bond pad. Manufacturing this mux/demux architecture is typically less expensive and more reliable than connecting a bond pad to each wire.
In FIG. 1, for instance, an array of wires 102 with wires and spacing well above 1000 nanometers, is electrically connected to one bond pad 104. Wires 106 of the array 102 can be communicated with separately using a binary mux/demux architecture shown at numeral 108. This mux/demux 108 has four different address circuits 110, 112, 114, and 116, each of which communicates with a set of transistors 118 through two address lines. The signals sent to each set of two address lines are complimentary. These address circuits can turn on or off the transistors 118 to which they are connected. By turning the transistors 118 on and off, only one of the wires 106 can be permitted to pass a measurable current from a power supply 120 to the bond pad 104.
For example, a measurable current can travel from the power supply 120 through a third wire 122 (counting from top) to the bond pad 104 only if all four of the transistors 118 that are in contact with the third wire 122 are turned on. The transistors 118 of the third wire 122 are turned on by turning the address circuit 110 on, the circuit 112 on, the circuit 114 off, and the circuit 116 on. When on, the transistors 118 on the “Logical YES” side of each of the address circuits turn on and on the “Logical NOT” side turn off, and vice-versa. Address wires 124, 126, 128, and 130 are used to turn the address circuits 110, 112, 114, and 116 on or off, respectively.
Using this type of mux/demux architecture, a number of address elements (here transistors 118) are used for each wire. This number of elements can increase with higher numbers of wires in an array. For the array 102, which has only 16 wires, four transistors 118 are used for each of the wires 106. For an array having 32 wires, this architecture uses five address elements. For 64 wires, it uses six address elements, for 128 seven, for 256 eight, for 512 nine, and so forth.
Another type of mux/demux includes h-hot architectures. H-hot architectures control wires of an array with a set number (h) of address elements and address wires controlling each wire. For example, if an h-hot mux/demux architecture has m address wires and h address elements on each wire (e.g., transistors), the maximum array size is the combination of h out of m: (Cmh).
The mux/demux architecture 108 (and typical h-hot architectures) use address elements (like transistors, diodes, and resistors) built using multiple patterned layers and circuit elements (like address lines and wires). Aligning these elements (or layers) with the wires 106 can be accomplished with typical processing machines if the wires 106 of the array 102 are large enough and spaced far enough apart. For narrow wires and spaces, however, the mux/demux architecture 108 may not be able to align the address elements with sufficient accuracy to meet a tolerance of the narrow wires and spaces.
There is, therefore, a need for a system and method capable of communicating with arrays having small wires and spaces that is reliable, less expensive, and/or more production-friendly than permitted by present-day techniques.
The same numbers are used throughout the disclosure and figures to reference like components and features.